1. Field of the Invention
The present invention relates to a substrate processing apparatus configured to process a substrate using plasma and a semiconductor device manufacturing method for forming a film.
2. Description of the Prior Art
Generally, a film is formed on a surface of a wafer by supplying a raw material to the surface of the wafer and heating the surface of the wafer. However, since recent miniature silicon devices are required to be manufactured at a low temperature, plasma is currently used as replacement of thermal energy.
Up to now, in a substrate processing apparatus using plasma, a plasma generating unit is installed at a place spaced apart from a wafer, and an active species (radical) generated by the plasma generating unit is transferred to a wafer accommodating unit, so as to protect a wafer from plasma damages.
However, in the case where the plasma generating unit is installed apart from a wafer, a long transfer passage is necessary to transfer an active species from the plasma generating unit to the wafer accommodating unit, so that the active species is easily deactivated on the way to the plasma generating unit and it is difficult to improve the film quality and reduce the film forming time.
Thus, in another method of the related art, a plasma generating unit is installed at a place close to a wafer, and an active species is supplied to the wafer from a place close to the wafer, in order to improve the film quality and film forming time (for example, refer to Patent Document 1).
FIG. 13A and FIG. 13B illustrate an exemplary structure of a process furnace of a substrate processing apparatus of the related art. FIG. 13A is a side sectional view, and FIG. 13B is a cross-sectional view.
A process furnace 1 includes a reaction tube 4 in which a plurality of wafers 2 are stacked; a gas supply system 5 configured to supply a predetermined reaction gas to the reaction tube 4; a gas discharge system 7 configured to discharge the inside atmosphere of a process chamber 6; a radio frequency (RF) unit 8 configured to output predetermined RF power; first and second electrodes 9 and 10 to which RF power is applied from the RF unit 8 for exciting process gas into plasma; and a control device 12 configured to control the gas supply system 5, the gas discharge system 7, and the RF unit 8. In a substrate processing operation, a boat 3 in which a plurality of wafers 2 are stacked is inserted into the reaction tube 4.
The gas supply system 5 includes a nozzle 5a extending along the stacked direction of the wafers 2, and the nozzle 5a includes a plurality of gas supply holes 5b. In addition, the first and second electrodes 9 and 10 are installed in a manner such that a process gas supplied through the first gas supply holes 5b can flow between the first and second electrodes 9 and 10. The control device 12 controls the RF unit 8 to apply predetermined RF power to the first and second electrodes 9 and 10 for generating plasma.
The control device 12 maintains the pressure inside the reaction tube 4 at a constant level by controlling the gas discharge system 7. The control device 12 controls the RF unit 8 to apply a voltage across the first and second electrodes 9 and 10. The control device 12 controls the gas supply system 5 to supply a desired process gas to a gap between the first and second electrodes 9 and 10 from the first gas supply holes 5b of the nozzle 5a, in order to generate plasma between the first and second electrodes 9 and 10. The process gas is excited by this plasma, and thus an active species is generated. The active species is supplied to the wafers 2 from sides of the wafers 2 to process the wafers 2. In this way, high-quality films can be formed on the wafers 2, and film forming time can be reduced.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2005-56891
However, in the related art, when a process gas is supplied from a gas supply system, since upper and lower stacked substrates are at the same electric potential and the pressure inside a process chamber is uniform, it is difficult for an active species to enter between the substrates, and thus the center parts of the substrates are less processed than the other parts of the substrates.
In a method proposed to solve theses problems, a predetermined amount of process gas is supplied at a high flowrate. Although this method is used, the amount of an active species supplied between substrates is still insufficient.